The personal computer provides a platform on which anyone willing to invest the effort in programming can write programs that can carry out almost any desired function, limited only by the constraints of the programming language, the operating environment, and the hardware on which the program is executed. The manufacturers of personal computers and those providing the operating systems and programming tools place little restriction on how a user chooses to use their respective products. However, there are instances where it may be important to restrict how computing devices are used. In the broadest sense, a computing device may be any device that includes a processor that executes machine instructions stored in a memory to perform some function. Thus, a computing device can have a dedicated function, or may be very general in functionality, just as a typical personal computer is.
One type of computing device that is similar in some ways to a personal computer, yet is more specialized in its primary function, is a game console. Although game consoles can often perform other functions, their primary function is to execute machine instructions to enable one or more users to play various types of games. The companies that produce game consoles have a substantial interest in controlling various aspects of any game software that is executed on their game consoles. For example, they will want to ensure that the quality of the game software meet certain specifications. Since the manufacturers of game consoles typically license other companies to produce game software that is usable on their game consoles, it is preferable to preclude unlicensed software from being used on the game console. Aside from the loss of revenue that would result if unlicensed software is played on a game console, there is also an issue of maintaining quality control over software that is played on the game console. Also, it will be important to ensure that software licensed for use on a game console has not been modified after it was approved for distribution and released to the public. Without such controls being applied, game software might be “hacked” to add pornography or other features or functionality that was not included in the authorized software when it was originally approved for distribution by the software company under license from the maker of the game console. In addition, the game console should be capable of enforcing limitations regarding geographic regions associated with a game console that preclude playing game software licensed for one geographic region on a game console sold for use in a different region.
Other policies that should be enforced on a game console relate to classifications of game software based upon its level of violence, language used, sexual content, and other criteria. The Entertainment Software Rating Board (ESRB) is an organization that reviews and rates game software and categorizes the software by assigning it an age group category for which the game software is believed to be suitable. These age group categories include: “Everyone” (suitable for all age groups), “Adult” (ages 18 and older), “Mature” (ages 17 and older), “Teen” (ages 13 and older), and “Early Childhood” (ages 3 and older). Game software producers who subscribe to this service receive a rating from the ESRB and agree to include a corresponding rating symbol on the packaging for their software. The rating is also included in the game software. Game consoles can be selectively programmed by an authorized user not to play game software that has a rating for any age group above a desired level. Thus, a parent might set up a game console to only play game software that is rated to be suitable for Everyone. It is important that the game console prevent a user from circumventing any restriction regarding the play of software games beyond the category last set by an authorized user on the console.
There are several different approaches that can be used to enforce policies relative to the software that is executed on a computing device such as a game console. For example, a hardware component such as a resistor that has one of several different resistance values can be employed in the computing device to designate the region for which software is authorized. Software from a different region will then test for the resistance value and will not execute on the game console because the resistance value detected in the game console is not within a predefined tolerance of an expected value.
Other hardware-related techniques have been used for authenticating software plug-in cartridges used to store game software. In one prior art game system, the housing of authorized software game cartridges and a corresponding receptacle in the game console were formed to prevent cartridges of a different shape from being inserted into the receptacle. In addition, the game console and any authorized cartridge included a processor and a read only memory (ROM) that stored specific data needed to authenticate the cartridge. If the result of a calculation carried out by both the processor in the game console and the processor in the cartridge did not match, the game console would not enable the software for the game stored in the cartridge to execute on the game console.
Because of the richness of the graphics and the complexity of games designed to run on current generation game consoles, the game software is more efficiently distributed on either optical storage media, such as compact disc-read only memory discs (CDROMs) or digital versatile discs (DVDs). Accordingly, alternative approaches that do not rely upon hardware in the software component must be employed, since the discs do not provide the option of including other hardware components for use in authenticating the software and enforcing security and usage policies. Details of how each game console manufacturer has chosen to address this problem are not readily available. Clearly, it will be desirable to employ the data stored on the disc to determine if the software has been altered and to enforce security polices and usage of software executed on a game console.
A solution of this problem that is applicable to game software and game consoles may be equally applicable to many other types of computing devices in which control of software and data that is executed by the computing device is desired. For example, the security policies relating to use of satellite receivers, portable telephones, and other devices that may include a processor might also be enforced by the same approach employed on game consoles. Accordingly, a solution to this problem regarding securing game software for play on consoles in accord with a desired policy is also readily adapted for use in controlling how software and other digital data might be used on these other types of computing devices.